The influence of electrowetting on the behavior of impacting droplets on superhydrophobic surfaces

Hoek, H.J. and Nijenhuis, A.K. te (2015) The influence of electrowetting on the behavior of impacting droplets on superhydrophobic surfaces.

Abstract:In this research the concept of bouncing droplets on superhydrophobic surfaces is combined with electrowetting. By applying a voltage it is possible to reduce the number of times the droplet bounces, or even suppress the bouncing by trapping the droplet on the surface. With the use of electrowetting, it is observed that the radius of the droplet increases with voltage. It is shown that this relation is linear. The linear energies are compared with and without electrowetting. It is observed that the unaccounted dissipation increases with the voltage. The loss in linear energy before and after the fi�rst bounce is investigated and it is shown that this energy di�fference goes quadratically with voltage as predicted by the electrowetting equation. The voltage at which a droplet is just trapped to the surface is called the critical voltage. It is shown that the critical voltage increases as the height increases. A greater height means more linear energy that has to be dissipated on the surface the make the droplet stick. However, due to the oscillations in the droplet, a greater fall height, generally, still means a greater critical voltage. The phenomenon of trapping droplets using electrowetting can be extended to a two dimensional situation in which bouncing droplets can be steered. This is done by using a double gap electrode where the droplet impacts on one side of the gap, and a voltage is applied on the other two electrodes at the other side of the gap. Found is that the droplet jumps towards the electrodes over which the voltage is applied.
Item Type:Essay (Bachelor)
Faculty:TNW: Science and Technology
Subject:33 physics
Programme:Applied Physics BSc (56962)
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